US20250170637A1 - Soluble core for high-pressure casting and manufacturing method thereof - Google Patents

Soluble core for high-pressure casting and manufacturing method thereof Download PDF

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Publication number
US20250170637A1
US20250170637A1 US18/842,701 US202318842701A US2025170637A1 US 20250170637 A1 US20250170637 A1 US 20250170637A1 US 202318842701 A US202318842701 A US 202318842701A US 2025170637 A1 US2025170637 A1 US 2025170637A1
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core
ratio
high pressure
chemical salt
soluble
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US18/842,701
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English (en)
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Kyoko Hirokawa
Jun Su Kim
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/10—Cores; Manufacture or installation of cores
    • B22C9/105—Salt cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/002—Castings of light metals
    • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
    • B22D29/001—Removing cores
    • B22D29/003—Removing cores using heat

Definitions

  • the present invention relates to a method for manufacturing a soluble core for high pressure casting and a soluble core manufactured by the manufacturing method, and more specifically relates to a method for manufacturing a soluble core for high pressure casting using a water-soluble chemical salt having a lower melting point than a cast alloy, and a soluble core having a complex internal shape manufactured by the manufacturing method.
  • a core technology is required. That is, in a case of gravity casting, a collapsible core using hard sand and the like is generally used, or, as in U.S. Pat. No. 4,629,708, there is used a technology to carry out casting using a water-soluble chemical salt and melt the water-soluble chemical salt into water or steam after casting.
  • Korean Patent Publication No. 10-2002-0009334 discloses a high pressure casting core technology using a chemical salt having a lower melting point than a cast alloy.
  • the casting product manufactured by the technology can be usefully applied to manufacturing of die casting products of relatively low heat capacity cast alloys, such as aluminum and magnesium alloys, with a thickness of about 25 mm, but there are limitations in applying the technology to manufacturing of high pressure casting products, such as squeeze casting and die casting, of a thick-walled product having a high heat capacity with a thickness of 25 mm or more or a product with a large change in thickness.
  • the present invention has been created to solve the problems of the prior art as described above, and an object of the present invention is to provide a method for manufacturing a soluble core for high pressure casting, which can perform high pressure casting of a thick-walled product having a complex shape implemented inside using a core for high pressure casting manufactured with a water-soluble chemical salt having a lower melting point than a cast alloy and a high heat capacity.
  • Another object of the present invention is to provide a method for manufacturing a core for high pressure casting, which includes injecting a molten chemical salt, in which a heat-resistant hard powder is uniformly dispersed and mixed so that the molten chemical salt has a melting point 140° C. to 260° C. lower than the melting point of the cast metal and a heat capacity of 90 J/(mol ⁇ K) or more, into a core mold and solidifying the molten chemical salt to manufacture the core, and a method for extracting the core by heating thereof in a temperature range equal to or lower than the melting point at which a casting using the soluble core for high pressure casting manufactured by the above manufacturing method is not thermally deformed.
  • one aspect of the present invention relates to a method for manufacturing a soluble core for high pressure casting, including: a step of manufacturing a water-soluble chemical salt mixture having a melting temperature of 390° C. to 520° C.; a step of uniformly dispersing and mixing a heat-resistant hard powder into the water-soluble chemical salt mixture to manufacture a molten chemical salt having a heat capacity of 90 J/(mol ⁇ K) or more; and a step of injecting the manufactured molten chemical salt into a core mold and solidifying the manufactured molten chemical salt to manufacture a core.
  • Casting products manufactured by a technology in the related art can only be applied to manufacturing of die casting products of relatively low heat capacity cast alloys, such as aluminum and magnesium alloys, with a thickness of about 25 mm, and thus there has been a problem that there is a limitation of applying the technology in the related art to high pressure casting products, such as squeeze casting and die casting, of a thick-walled product having a high heat capacity with a thickness of 25 mm or more or products with a large change in thickness.
  • the soluble core manufactured by high pressure casting according to the present invention is characterized in that it is possible to form a thick-walled product with a casting thickness of about 40 mm, and the boundary surface of the core is transferred as it is without melting and thermal change, so that it is advantageous in high pressure casting of a thick-walled product having a complex shape implemented inside.
  • the water-soluble chemical salt mixture in the present invention may include any one or more selected from the group consisting of a chloride-based chemical salt, a carbide-based chemical salt, and a sulfide-based chemical salt.
  • the chloride-based chemical salt may include any one or more selected from the group consisting of NaCl, KCl, MnCl 2 , CaCl, MgCl 2 , and LiCl, but is not limited thereto.
  • the carbide-based chemical salt may include any one or more selected from the group consisting of K 2 CO 3 , Li 2 CO 3 , and Na 2 CO 3 , but is not limited thereto.
  • the sulfide-based chemical salt may include any one or more selected from the group consisting of K 2 SO 4 , Na 2 SO 4 , and Li 2 SO 4 , but is not limited thereto.
  • the heat-resistant hard powder in the present invention may include any one or more selected from the group consisting of TiO 2 , Al 2 O 3 , and ZrSiO 4 .
  • the water-soluble chemical salt mixture in the present invention may have a melting point 140° C. to 260° C. lower than the melting point of the cast metal.
  • a melting temperature of the water-soluble chemical salt mixture may be 390° C. to 520° C. by controlling a mixing ratio of any one or more selected from the group consisting of a chloride-based chemical salt, a carbide-based chemical salt, and a sulfide-based chemical salt.
  • the cast metal in the present invention may be, but is not limited to, an aluminum alloy or a magnesium alloy.
  • the melting point of the core is lower than the temperature of the molten metal (670° C. to 720° C.) for casting, which is about 390° C. to 520° C., but the heat capacity of the core is 90 J/(mol ⁇ K) or more, which is 2.5 times or more the heat capacity of the aluminum alloy (24.20 J/mol ⁇ K) and the magnesium alloy (24.869 J/(mol ⁇ K), both of which are cast metals, and the thermal conductivity coefficient is about 2.4 ⁇ 10 ⁇ 4 to 1.2 ⁇ 10 ⁇ 3 cal/scm, which is about 1/100 to 1/200 of the thermal conductivity coefficient of the steel (1.8 ⁇ 10 ⁇ 1 cal/scm) for the casting mold material, so the cast metal, which is instantly filled during high pressure casting, begins to cool rapidly.
  • the thermal conductivity coefficient of the core is lower than that of the steel, which is the mold material, most of the heat of the molten metal is transferred to the mold, and since the heat capacity of the core is high, it takes a lot of time and heat for the core to melt. Therefore, when the core reaches the melting temperature, a solidified layer of cast metal is formed on the boundary surface between the core and the cast metal, and as more time passes, a part of the surface of the core gradually melts, so the cast metal can be formed to have complex internal shapes.
  • a method for extracting a core is as follows: when a casting that has been cast by high pressure using the core is slowly heated at a temperature of 390° C. to 520° C. or higher for 3 to 5 minutes, unlike high pressure casting, heat is transmitted to the interior of the core, so that the core soon becomes molten and flows out of the casting, allowing the core to be easily removed from the casting.
  • the material removed in this way can be reused as a core material.
  • the method for manufacturing a soluble core for high pressure casting in the present invention may further include a step of installing the manufactured core in a high pressure casting mold, performing high pressure casting of a molten metal, and then performing heating to a temperature equal to or less than the melting point of the cast alloy to extract the molten core.
  • Another aspect of the present invention relates to a soluble core for high pressure casting manufactured by the above manufacturing method.
  • Another aspect of the present invention relates to a soluble core for high pressure casting, characterized in that the core is formed by uniformly dispersing and mixing a heat-resistant hard powder into a water-soluble chemical salt mixture having a melting point 140° C. to 260° C. lower than the melting point of the cast metal, the mixture including any one or more selected from the group consisting of a chloride-based chemical salt, a carbide-based chemical salt, and a sulfide-based chemical salt, to form a molten chemical salt having a heat capacity of 90 J/(mol ⁇ K) or more.
  • Another aspect of the present invention relates to a method for extracting a soluble core for high pressure casting, characterized in that the soluble core for high pressure casting is heated to a temperature equal to or less than the melting point of the product after high pressure casting, melted, extracted, and then washed with water.
  • the soluble core for high pressure casting in the present invention can be manufactured by mixing any one or more selected from the group consisting of a chloride-based chemical salt, a carbide-based chemical salt, and a sulfide-based chemical salt such that the melting temperature of the water-soluble chemical salt mixture becomes 390° C. to 520° C.
  • the core can be manufactured by uniformly dispersing and mixing a heat-resistant hard powder into the water-soluble chemical salt mixture such that the heat capacity of the molten chemical salt becomes 90 J/(mol ⁇ K) or more.
  • the mixing ratio for manufacturing the water-soluble chemical salt mixture can be changed in various ways and can have various embodiments. Since it is possible if the melting temperature range of the chemical salt mixture for a core (390° C. to 520° C.) and the heat capacity of the molten chemical salt are 90 J/(mol ⁇ K) or more, it is not limited to specific components and mixing ratios.
  • the water-soluble chemical salt mixture may be formed of KCl:MnCl 2 :NaCl in a ratio of 45.5:33.5:20, CaCl 2 :KCl:MgCl 2 :NaCl in a ratio of 41.6:2.2:8.8:47.4, CrCl 2 :KCl in a ratio of 60:40, K 2 CO 3 :Li 2 CO 3 :Na 2 CO 3 in a ratio of 25:43.5:31.5, K 2 CO 3 :MgCO 3 in a ratio of 55:45, K 2 SO 4 :Li 2 SO 4 in a ratio of 18:82, K 2 SO 4 :Na 2 SO 4 of 75:25, LiCl:Li 2 SO 4 :Li 2 CO 3 in a ratio of 52.9:27.2:19.8, LiCl:Li 2 SO 4 :NaCl in a ratio of 54.8:29:16.1, LiCl:Li 2 CO 3
  • a molten chemical salt mixture solution manufactured by uniformly dispersing and mixing heat-resistant hard ceramic particles such as TiO 2 , Al 2 O 3 , and ZrSiO 4 hereto so that the heat capacity becomes 90 J/(mol ⁇ K) or more is injected into a core mold and solidified to manufacture a core.
  • heat-resistant hard ceramic particles such as TiO 2 , Al 2 O 3 , and ZrSiO 4 can be additionally uniformly dispersed, and by adding 10% to 40% (wt %) of hard ceramic powder, the heat capacity of the core can be further increased, and the mechanical strength can be improved.
  • a solution obtained by dispersing and mixing a hard ceramic powder in this way is injected into a core mold and solidified to manufacture a soluble core for high pressure casting.
  • the method for manufacturing a core by dispersing a heat-resistant hard ceramic powder in a water-soluble chemical salt having a melting point 140° C. to 260° C. lower than the melting point of a cast metal and a heat capacity of 90 J/(mol ⁇ K) or more is a very useful technology that can easily manufacture a core for high pressure casting of metals such as aluminum and magnesium, and the method for extracting a core from casting can also be simply performed by heating and extracting thereof at a temperature equal to or lower than the melting point of the cast metal, and since the core material can be recycled, it is very effective in terms of productivity and economy.
  • a thick-walled product having a complex shape implemented inside can be casted under high pressure using a core for high pressure casting manufactured with a water-soluble chemical salt having a lower melting point than the cast alloy and a high heat capacity of the present invention.
  • FIG. 1 shows a shape of a core for high pressure casting (symbol CL-460) according to an embodiment of the present invention.
  • FIG. 2 shows a front view and a side view of a high pressure casting mold and a core mounted on a specimen used in an embodiment of the present invention.
  • FIG. 3 shows a thermal analysis graph of soluble core (symbol CL-460) according to an embodiment of the present invention.
  • FIG. 4 shows a photograph of a high pressure cast product by applying a soluble core (symbol CL-460) according to an embodiment of the present invention.
  • FIG. 5 shows a photograph of a core after heating and extraction after high pressure casting by applying a soluble core (symbol CL-460) according to an embodiment of the present invention.
  • FIG. 6 shows a photograph of a boundary surface of a core after heating and extraction of a high pressure cast product by applying a soluble core (symbol CL-460) according to an embodiment of the present invention after heating and extracting the core.
  • FIG. 7 shows a thermal analysis graph of a soluble core (symbol SL-512) according to an embodiment of the present invention.
  • a thermal analysis method used here is Differential Scanning calorimetry (DSC), which is a method of measuring the difference in energy input to a sample and a reference material as a function of temperature while changing the temperatures of the sample and the reference material.
  • DSC Differential Scanning calorimetry
  • FIG. 8 shows a photograph of the boundary surface of a core after heating and extraction of a high pressure cast product by applying a soluble core (symbol CL-512) according to an embodiment of the present invention.
  • the thermal analysis result of the soluble core for high pressure casting manufactured in this way shows that melting starts at 460° C. (melting point 456° C.), as shown in FIG. 3 .
  • the core manufactured in this way was mounted in a high pressure casting mold with a casting thickness of about 40 mm, as shown in FIG. 2 , and then the performance of the core was evaluated by a high pressure die casting method using AC4C aluminum alloy.
  • AC4C aluminum alloy heated to 700° C. was used, the gate injection speed of the molten metal was 55 m/sec, and the final injection pressure was 980 kg/cm 2 .
  • the casting was heated at a temperature of 500° C. for about 5 minutes to melt and extract the core, and then washed with water.
  • FIG. 5 shows a shape of a casting obtained by heating and extracting a core after high pressure casting by the manufacturing method. It can be seen that it is possible to form a thick-walled product with a casting thickness of about 40 mm, and the shape of the core is transferred as it is without melting change. Also, as shown in FIG. 6 , it can be seen that the casting surface is clean.
  • the thermal analysis result of the soluble core for high pressure casting manufactured in this way shows that a peak due to crystal structure changes at 428° C. and a peak due to melting latent heat starts at 512° C. (melting point 512° C.) as shown in FIG. 7 .
  • the core manufactured in this way was mounted in a high pressure casting mold, as shown in FIG. 2 , and then the performance of the core was evaluated by a high pressure die casting method using AC4C aluminum alloy.
  • AC4C aluminum alloy heated to 700° C. was used, the gate injection speed of the molten metal was 55 m/sec, and the final injection pressure was 980 kg/cm 2 .
  • the casting was heated at a temperature of 530° C. for about 10 minutes to melt and extract the core, and then washed with water.
  • FIG. 8 is a cross-section of a casting manufactured by high pressure casting of a thick-walled product by the above-described manufacturing method and then heating and extracting a core. It can be seen that it is possible to form a thick-walled product with a casting thickness of about 40 mm, and the boundary surface of the core is transferred as it is without melting or thermal change.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Mold Materials And Core Materials (AREA)
US18/842,701 2022-03-03 2023-02-28 Soluble core for high-pressure casting and manufacturing method thereof Pending US20250170637A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
KR1020220027303A KR102576599B1 (ko) 2022-03-03 2022-03-03 고압주조용 가용성 중자 제조 및 이를 이용한 주조방법
KR10-2022-0027303 2022-03-03
PCT/JP2023/010489 WO2023167342A1 (ja) 2022-03-03 2023-02-28 高圧鋳造用可溶性中子及びその製造方法

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US (1) US20250170637A1 (https=)
EP (1) EP4487978A4 (https=)
JP (1) JPWO2023167342A1 (https=)
KR (1) KR102576599B1 (https=)
CN (1) CN118891116A (https=)
WO (1) WO2023167342A1 (https=)

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1055737A (en) 1964-03-25 1967-01-18 Wellworthy Ltd Improvements in casting processes
DE1483641C3 (de) 1965-06-12 1973-10-11 Karl Schmidt Gmbh, 7107 Neckarsulm Wasserlösliche Salzkerne
US3963818A (en) 1971-10-29 1976-06-15 Toyo Kogyo Co., Ltd. Water soluble core for pressure die casting and process for making the same
GB8314089D0 (en) 1983-05-20 1983-06-29 Doulton Ind Products Ltd Moulding
US4840219A (en) * 1988-03-28 1989-06-20 Foreman Robert W Mixture and method for preparing casting cores and cores prepared thereby
KR20000006623A (ko) * 1999-07-06 2000-02-07 이인호 고압주조용붕괴성코어의제조방법과코어및그코어의추출방법
KR100400132B1 (ko) 2000-07-26 2003-09-29 주식회사 기술연합 주조용 용해성 코어의 제조방법과 코어 및 그 코어의추출방법
JP5391450B2 (ja) * 2009-08-01 2014-01-15 富山県 鋳造用コア
JP2016064436A (ja) * 2014-09-25 2016-04-28 スズキ株式会社 鋳造用塩中子の製造方法および鋳造用塩中子

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KR102576599B1 (ko) 2023-09-08
WO2023167342A1 (ja) 2023-09-07
EP4487978A4 (en) 2026-04-29
CN118891116A (zh) 2024-11-01
JPWO2023167342A1 (https=) 2023-09-07
EP4487978A1 (en) 2025-01-08

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